Karak, Bidya Binay and Choudhuri, Arnab Rai (2013) Studies of grand minima in sunspot cycles by using a flux transport solar dynamo model. In: RESEARCH IN ASTRONOMY AND ASTROPHYSICS, 13 (11). pp. 1339-1357.
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Abstract
We propose that grand minima in solar activity are caused by simultaneous fluctuations in the meridional circulation and the Babcock-Leighton mechanism for the poloidal field generation in the flux transport dynamo model. We present the following results: (a) fluctuations in the meridional circulation are more effective in producing grand minima; (b) both sudden and gradual initiations of grand minima are possible; (c) distributions of durations and waiting times between grand minima seem to be exponential; (d) the coherence time of the meridional circulation has an effect on the number and the average duration of grand minima, with a coherence time of about 30 yr being consistent with observational data. We also study the occurrence of grand maxima and find that the distributions of durations and waiting times between grand maxima are also exponential, like the grand minima. Finally we address the question of whether the Babcock-Leighton mechanism can be operative during grand minima when there are no sunspots. We show that an alpha-effect restricted to the upper portions of the convection zone can pull the dynamo out of the grand minima and can match various observational requirements if the amplitude of this alpha-effect is suitably fine-tuned.
| Item Type: | Journal Article |
|---|---|
| Publication: | RESEARCH IN ASTRONOMY AND ASTROPHYSICS |
| Publisher: | NATL ASTRONOMICAL OBSERVATORIES, CHIN ACAD SCIENCES |
| Additional Information: | copyright for this article belongs to Authors |
| Keywords: | magnetic fields; (magnetohydrodynamics:) MHD; Sun: magnetic fields; (Sun:) sunspots |
| Department/Centre: | Division of Physical & Mathematical Sciences > Physics |
| Date Deposited: | 28 Nov 2013 11:46 |
| Last Modified: | 28 Nov 2013 11:46 |
| URI: | http://eprints.iisc.ac.in/id/eprint/47840 |
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